Features and Benefits
- Operates with Power Blocks, DRMOS or External Gate Drivers and MOSFETs
- Constant Frequency Voltage Mode Control with Accurate Current Sharing
- ±0.75% 0.6V Voltage Reference
- Differential Remote Output Voltage Sense Amplifier
- Multiphase Capability—Up to 12-Phase Operation
- Programmable Current Limit
- Safely Powers a Prebiased Load
- Programmable or PLL-Synchronizable Switching Frequency Up to 1.25MHz
- Lossless Current Sensing Using Inductor DCR or Precision Current Sensing with Sense Resistor
- VCC Range: 3V to 5.5V
- VIN Range: 3V to 24V
- Power Good Output Voltage Monitor
- Output Voltage Tracking Capability
- Programmable Soft-Start
- Available in a 32- Pin 5mm × 5mm QFN Package
The LTC3860 is a dual, PolyPhase® synchronous stepdown switching regulator controller for high current distributed power systems, digital signal processors, and other telecom and industrial DC/DC power supplies. It uses a constant frequency voltage mode architecture combined with very low offset, high bandwidth error amplifiers and a remote output sense differential amplifier for excellent transient response and output regulation.
The controller incorporates lossless inductor DCR current sensing to maintain current balance between phases and to provide overcurrent protection. The chip operates from a VCC supply between 3V and 5.5V and is designed for stepdown conversion from VIN between 3V and 24V to output voltages between 0.6V and VCC – 0.5V.
The TRACK/SS pins provide programmable soft-start or tracking functions. Inductor current reversal is disabled during soft-start to safely power prebiased loads. The constant operating frequency can be synchronized to an external clock or linearly programmed from 250kHz to 1.25MHz. Up to six LTC3860 controllers can operate in parallel for 1-, 2-, 3-, 4-, 6- or 12-phase operation.
The LTC3860 is available in a 32-pin 5mm × 5mm QFN package.
- High Current Distributed Power Systems
- Digital Signal Processor and ASIC Supplies
- Telecom Systems
- Industrial Power Supplies
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (2)
Demonstration circuit DC1755A provides the user with two high current dual phase synchronous buck converters driven by the LTC3860. These buck converters provide outputs of 1.5V/50A and 1.2V/50A over an input voltage range of 6V to 14V and a switching frequency of 500kHz. The board can be easily modified for a 4-phase, single VO, 100A supply. The power stage for each phase consists of the tri-state PWM compatible 6mm × 6mm Fairchild DrMOS module and a 0.47μH 13.2mm × 12.8mm iron powder type inductor from Würth. A high density, two sided drop-in layout is used. The entire converter, excluding the bulk output and input capacitors, fits within a 2.25” × 1.38” area on the board.
Demonstration circuit DC1184A is a dual output voltage mode synchronous buck converter featuring the LTC3860EUH. This board provides two outputs of 1.2V/25A and 1.8V/25A from an input voltage of 10V to 14V at a switching frequency of 500kHz. The power stage consists of the Renesas R2J20602NP which is a tri-state PWM compatible 8mm × 8mm DrMOS and a 0.47µH 13.2mm × 12.8mm iron powder type inductor from Wurth. An on-board 5V LT1616 buck regulator provides the 5V bias for the LTC3860 and the DrMOS.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.
To open the project file for this circuit:
Step 1: Download and install LTpowerCAD on your computer.
Step 2: Click on the link(s) in the section below to download part-specific project files.
Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.
LTpowerCAD Project Files
Design tools for the following parts are available in LTpowerCAD:
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.